Add NewMachPort() and its test, and switch call sites to use it

util/mach/child_port_handshake.cc

 // Copyright 2014 The Crashpad Authors. All rights reserved.
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
 // You may obtain a copy of the License at
 //
 //     http://www.apache.org/licenses/LICENSE-2.0
 //
 // Unless required by applicable law or agreed to in writing, software
 // distributed under the License is distributed on an "AS IS" BASIS,
@@ skipping 108 matching lines @@
     return MACH_PORT_NULL;
   }
 
   if (!LoggingWriteFD(pipe_write, service_name.c_str(), service_name_length)) {
     LOG(WARNING) << "no client check-in";
     return MACH_PORT_NULL;
   }
 
   // A kqueue cannot monitor a raw Mach receive right with EVFILT_MACHPORT. It
   // requires a port set. Create a new port set and add the receive right to it.
-  mach_port_t server_port_set;
-  kr = mach_port_allocate(
-      mach_task_self(), MACH_PORT_RIGHT_PORT_SET, &server_port_set);
-  MACH_CHECK(kr == KERN_SUCCESS, kr) << "mach_port_allocate";
-  base::mac::ScopedMachPortSet server_port_set_owner(server_port_set);
+  base::mac::ScopedMachPortSet server_port_set(
+      NewMachPort(MACH_PORT_RIGHT_PORT_SET));
+  CHECK_NE(server_port_set, kMachPortNull);
 
   kr = mach_port_insert_member(mach_task_self(), server_port, server_port_set);
   MACH_CHECK(kr == KERN_SUCCESS, kr) << "mach_port_insert_member";
 
   // Set up a kqueue to monitor both the server’s receive right and the write
   // side of the pipe. Messages from the client will be received via the receive
   // right, and the pipe will show EOF if the client closes its read side
   // prematurely.
   base::ScopedFD kq(kqueue());
   PCHECK(kq != -1) << "kqueue";
@@ skipping 195 matching lines @@
       bootstrap_look_up(bootstrap_port, service_name.c_str(), &server_port);
   BOOTSTRAP_CHECK(kr == BOOTSTRAP_SUCCESS, kr) << "bootstrap_look_up";
   base::mac::ScopedMachSendRight server_port_owner(server_port);
 
   // Check in with the server.
   kr = child_port_check_in(server_port, token, port, right_type);
   MACH_CHECK(kr == KERN_SUCCESS, kr) << "child_port_check_in";
 }
 
 }  // namespace crashpad